Transducer



S. KLEIN TRANSDUCER Aug. 12, 1958 Filed April 23. 1953 S IEFWED KLei/V TRANSDUCER Siegfried Klein, Paris, France, assignor to Charles Legorju, Saint-Maur, France Application April 23, 1953, Serial No. 350,594 Claims priority, application France December 29, 1952 Claims. (Cl. 179-113) In my prior United States Patent No. 2,7 68,246, issued on October 23, 1956, an apparatus for the transformation of electrical modulations into vibratory modulations is described, whereby a high frequency discharge modulated by suitable potentials occurs at the throat end of an exponential horn and vibrates the desired sounds.

Without any movable part or membrane, the apparatus air and produces the will reproduce without any difficulty the sharpest or highest-pitched sounds, provided of course that a suitable horn is available.

A novel feature consists essentially in that the highfrequency high-voltage transformer is integral with the emitter device and constitutes therewith a complete selfcontained unit adapted to be electrically connected to a high-frequency low-voltage oscillator.

According to one specific form of embodiment of the present invention, this high-frequency high-voltage transformer is disposed around the emitter electrode, thereby permitting not only to reduce the longitudinal dimensions of the apparatus but also to dispense with the cage-like element constituting the other electrode mounted around the emitter point, this other electrode consisting in the present instance of one winding of said transformer.

I According to another form of embodiment the emitter electrode is grounded and the other electrode is constituted by the secondary winding of the high-frequency high-voltage transformer; with this arrangement it is possible notably touse the low-voltage current for heating the emitter electrode, this solution affording several advantages. In this case the high-voltage terminal of the secondary is insulated.

Thus, as in the aforementioned prior patent, electrical discharges are obtained which can extend towards the second electrode and beyond the point of this second electrode when important modulations are produced,

1 without any risk of arcing as would be the case if this second electrode were not strongly insulated.

Either of these electrodes may be connected to the high-voltage high-frequency terminal, the other being earthed.

These various improvements will be better understood 7 if reference is made to the accompanying drawings forming part of this specification and illustrating diagrammatically by way of example a few forms of embodiment of the present invention.

In the drawings:

.Figures 1 to 4 show a few modified forms of the invention.

' Referring to Figure l, discharge electrode 31 is fitted in a small quartz tube 32; this quartz tube is embedded in the lower portion or inner end 33 of an exponential horn, also of quartz or like material, so as to form a chamber 35 in which a sufiicient vacuum is created. On

the other hand this chamber may also remain filled with air, the heat developed during the operation of the apparatus being such that the air pressure in chamber 35 ;;becomes sufiicient to constitute an efiicient insulating kmedium.

This assembly is surrounded by an earthed electrode 36, which may be of aluminum and form a casing having a sealed bottom consisting of an insulating plate 37, for instance of steatite or like refractory insulating material.

The platinum point 31 is connected to the secondary 38 of a high-frequency transformer the primary 39 of which has one end 40 connected to the central portion 41 of a coaxial conductor and the other end 43 connected to the peripheral electrically-conductive portion 44 of this coaxial conductor 42 connected to a source of modulated high frequency at a low potential (not shown), this peripheral portion 44 being earthed as shown. Preferably, a switch 45 will be inserted before the coaxial conductor so that the complete assembly consisting of the emitter proper with its high-frequency high-voltage transformer can be isolated at will.

In this form of embodiment the high-voltage highfrequency current is fed to discharge electrode 31 and the other electrode 36 is earthed, 'so that a corona discharge is provided at electrode 31L In the modified form of embodiment shown in Fig. 2, the same elements as in the arrangement of Fig. 1 are used, the only difference residing in that the windings 38 and 39 of the high-frequency high-voltage transformer are disposed coaxially around the platinum point 31 and that the other earthed electrode 36 is constituted by the rear portion of the secondary 39 which is earthed in this case.

In the modified embodiment of Fig. 3 the primary and secondary windings are still mounted coaxially to the discharge electrode 31 but the latter is earthed directly, whilst it is the high-voltage high-frequency portion of the secondary which constitutes the second electrode and surrounds more closely discharge electrode 31; voltage terminal 46 of the secondary is insulated.

The potential difference between the two electrodes is the same as in the preceding forms of embodiment described hereinabove since the discharge electrode is earthed it can be heated much more easily and economically than a point fed with high-voltage current.

In the form of embodiment illustrated in Fig. 4 the arrangement is substantially similar to that of Fig. 1, except in that the quartz member 47, cemented or otherwise sealed to the rear portion of discharge electrode 31 at 37, carries the windings 38, 39 and constitutes an integral self-contained assembly adapted to be electrically connected through a plugor like connector (not shown) to the coaxial conductor 42; small quartz tubes or sockets 48, 49, 50 receiving the ends of the various winding wires facilitate the electrical connections.

Of course, the various forms of embodiment of the invention shown and described herein are merely given by Way of illustration and should not be construed as limiting the purpose of the invention as many modifications may be brought thereto, as will be obvious to anybody conversant with the art, without departing from the spirit and scope of the invention as set forth in the appended claims.

What I claim is:

1. In combination a complete self-contained transducer unit and high frequency transmission line, said transducer unit comprising a horn having an electrically insulating portion defining the origin thereof, a discharge electrode having an exposed tip within the insulating portion and located at and obturating the horn origin, another electrode insulated from said discharge electrode located in a forward position with respect to said first electrode, a high frequency high voltage transformer comprising a primary and a secondary winding, connections between said transmission line and primary for exciting the same with low voltage high frequency oscillations modulated the highby the waves to be transduced and means for impressing the high frequency secondary potentials on said two electrodes to create a corona discharge at said discharge electrode.

2. The combination according 'to claim 1 wherein said other electrode surrounds said insulating portion and is grounded.

3. The combination according to claim 1 wherein said transformer is disposed around said horn and wherein said other electrode consists of one winding of said transformer.

4. The combination according to claim 1 wherein said other electrode consists of a winding around said insulating portion; said winding having one terminal electrically insulated. V Y

5. The combination according to claim 1 wherein said discharge electrode is grounded, said high frequency transformer is disposed upon said horn, said transformer having a secondary winding comprising said other electrode, the high voltage terminal of said secondary winding being insulated.

References Cited in the file of this patent UNITED STATES PATENTS 

